Tap holder



Nov. 28, 1933. A. J. GAUTHIER TAP HOLDER Filed June 7, 1929 //III Zlmento z duo: we

Patented Nov. 28, 1933 TAP HOLDER Adelard J. Gauthier, Detroit, Mich, assignor to Packard Motor Car Company, Detroit, Mich, a corporation of Michigan Application June 7, 1929. Serial No. 369,178

5 Claims.

This invention relates to tap holders, and more particularly to devices for holding taps for the multiple tapping of threads.

Heretofore, great difficulty has been experienced in the multiple tapping of threads where the taps are of different leads, and hence operate at different depths in a work piece. The stress and strain imposed upon taps when operating under such conditions results in either stripping the threads or breaking the tap or both.

The fault lies in a positive engagement of the taps with the work piece and the uniform speed of operation thereof regardless of the variation in the leads of the taps. Then, too, a very serious objection has been found in that where, for any cause, any one of the taps in a group become chocked, it invariably snaps or break". It is the aim of the present invention to overcome these objections.

An object of the invention is to provide a tap holder for the multiple tapping of threads having different leads.

Another object of the invention is to provide a tap holder for the multiple tapping of threads of different leads, having means providing the necessary pressure for starting the operation of the taps and compensating for the difference the leads thereof.

Another object of the invention is to provide a tap holder in which a spring furnishes the necessary pressure to start the tap and compensates for the depth in which the tap is operating in the work piece. 7

Another object of the invention is to provide a tap holder designed to relieve stress and strain on the tap when in operation in a work piece and when being removed from the work piece.

A further object of the invention is to provide a tap holder having a clutch adapted to be auto matically thrown out when an excessive load is imposed upon the tap or when the tap becomes chocked.

A further object of the invention is to provide a tap holder for the multiple tapping of threads of different leads without injury to the threads or to the taps.

Another feature of the invention is a tap holder having telescopic parts and the spring associated therewith to furnish'the necessary pressure for starting the taps and to compensate for the difference in the leads.

A further feature of the invention is a tap holder comprising a clutch adapted to retain the parts in operative relation, until an excessive load is imposed upon the tap, whereupon the parts become automatically disengaged.

Gther objects of the invention will appear from the following description taken in connection with the accompanying drawing, which forms a part of this specification, and in which:

Figure l is a longitudinal sectional view of a tap holder embodying the invention,

Figure 2 is a cross sectional view taken substantially on line 2--2, Figure l,

Figure 3 is a cross sectional view taken on line 3-3, Figure 1,

Figure 4 is a cross sectional view taken on line 4-4, Figure l, and

Figure 5 is a fragmentary view of the end of the shaft illustrating the rollersfor gripping the head of tap.

Referring to the drawing for more specific details of the invention, 10 represents a body portion having formed integral therewith a shank 11 provided with the conventional square 12. 'As shown, the body portion 10 is provided with shouldered portions 18 and 14 and radial openings 15, the object of which will hereinafter appear. The body portion is axially bored as indicated at 16, and positioned in the bore for reciprooation is a plunger 1'7 actuated by a coil spring 18. The plunger has a head 19 substantially in the form of a cone.

A sleeve 20 is positioned for rotation on the shoulder 14:, and formed in this sleeve to register with the radial openings 15 are recesses 21. As

shown, balls 22 are positioned in the openings 15 and the registering recesses 21 andthese balls in the sleeve is a, shoulder 26 engaging the sleeve 20 to retain it in position. The sleeve 24 is further provided with an inturned flange 2'7 and mounted for reciprocation in the sleeves 20 and 24 is a shaft 28. This shaft has formed thereon a shoulder 29 which provides a bearing for a to prevent relative rotation between the sleeve and the shaft. Positioned intermediate the washers 30 and 33 on the shaft 28 is a coil spring 34, the objects of which will hereinafter appear.

Normally, the spring 34 retains the washer 30 against the shoulder 29 on the shaft 28 and the inturned flange 27 on the sleeve 24:, also the washer 33 against the end of the sleeve 20 and the keys 32 in the shaft. It will be observed that the spring at and its connections with the shaft provide for reciprocatcry movement of the shaft, and retard the and outward movement thereof. The spri g performs the function of a cushion for te sha t upon movunent thereof in either direction, and also i shes the pressure necessary in starting the operation of the On the free end of the shaft is a clutch mechanism. As shown, the shaft is axilily bored as indicated at 35, and the shaft has a diametrical slot 36 communicating -th the bore. The stem or" a tap 87 fits snugly in the bore and the conventional square head 38 thereon engages the slot. Rollers are mounted in the slot. These rollers are oppositely disposed and are adapted to engage the head As shown, the rollers 39 have an axle l0 and adapted to engage guide ways 41, adjacent to the slots 36. The shaft 28 is externally threaded ted at 42 and mounted to travel upon the thread is a sleeve or collar 43 the interior of which is conical, and threaded in the sleeve 43 a collar 4.4 closely fitting the shaft. The sleeve 13 serves to press the rollers 39 in engagement with the square head 38 upon the stem of the tap.

Normally, the plunger actuated by the spring 18 presses the conical shaped 19 into point contact engagement with the balls 22 to ice the body of the holder to the sleeve 26 whichi locked to the shaft 28 against relative rotation by the keys 32. This structure insures the rota--.

tion of the body 10 and the 2Z8 concomi tantly'up to a predetermined load. When the predetermined load is reached, the torque imposed on the holder through the tap in the work piece causes calls 22 to move inwardly against the action of the spring pressed plun er 17 causing the plunger to retract, whereupon the balls 22 disengage the recesses 21 in the sleeve 20 and permit relative rotation between the head and the sleeve. stress or strain on the tap.

Although the invention has been described in connection with certain specific embodiments, the principles involved are or numerous other applications, as wil rea ily occur to persons skilled in the art. The invei tion is therefore to be limited only as indicated by the scope of the appended claims.

Having thus described the various features of my invention, what I claim as new and desire to secure by Letters Patent is:

1. A tool holder comprising driving a driven member, an automatic clutch This immediately relieves any positioned between the driving and driven members and provided with radially movable ball members engaging the driving and driven mem here, an axially movable tapered plug member in the driving member normally engaging each of the radially movable members at a single point, and spring means urging said plug axially in a directiontomaintain the ball members in an engaging relation with the driving and driven members.

2'. A tool holder comprising relatively movable parts, one of said parts having a chuck associated therewith, and an automatic clutch intermediate the parts including radially movable ball members engageable with the parts, an axially movable tapered plug member having point contact with each of the radially movable members, and spring means urging said plug axially in a direction to maintain the ball members in engaging relation with the parts.

3. A tool holder comprising a driving member having an axial bore and radial recesses therein in cornnunication, a tapered plug in the axial bore, spring means for biasing the. plug axially, a drivemember having radial recesses adapted to register with the radial recesses of the driving member, and balls having point contact with the plug and normally held in the registered recesses by the plug to afiect a driving connection between the driv ng and the driven members, but effective on over-loads to move the plug axially against the pressure of the spring means to allow the bodies to withdraw from the bores in one of the members to break the driving connection.

4. A tool holder comprising a driving member having an axial bore and radial recesses therein in communication with the bore, a spring pressed tapered plug in the axial bore, a driven member having radial recesses therein adapted to register with the radial recesses of the driving member, andspherical members normally held in the registered radial recesses of the driving and driven members by the spring pressed tapered plug to effect a driving connection between the driving and driven members, but effective on overloads to move the plug axially to allow the. spherical members to withdraw from the recesses in one of the members thereby breaking the driving connection.

5. A tool holder comprising a driving member having an axial bore and radial recesses in communication with the bore, a driven sleeve having radial recesses therein adapted to register with the recesses in the driving member, balls disposed in the registered radial recesses normally effective i to establish a driving connection between the driv ing and the driven members, and a spring pressed tapered plug in the axial bore having a point contact with the balls, said plug being yieldable on overloads to permit the balls to withdraw from I l the recesses in the sleeve to break; the driving connection.

ADELARD J. GAUTHIER. 

